Gas diffuser

ABSTRACT

A gas diffuser including a conically-shaped diffuser cone having a plurality of openings formed along the base circumference of the cone for liberating small gas bubbles. Connected to an opening formed in the apex of the cone is a hydrostatic leg depending therefrom. The length of the hydrostatic leg is designed such that during normal operation no gas will pass therethrough. The openings in the diffuser cone include an outer entrance opening and a recessed inner entrance opening. The inner opening is of square shape to release a small bubble. The top of the diffuser cone includes a unique seat and latch connecting arrangement that enables the diffuser to be installed in an opening in gas header pipes of varying diameters.

' United States Patent 1191 Goodman et al. Feb. 5, 1974 GAS DIFFUSER3,339,901 9/1967 Walker 261/124 1751 Brian Goodman, Overland Park;$252323 135233 @Ziliifiiii: :31. 261,121

Robert B. Higgins, Olathe; Frank M. Denham Overland Park an of PrimaryExaminer-Frank W. Lutter Kans' Assistant ExaminerSteven H. Markowitz[73] Assi nee: Ecod ne Corporation Chica 0, Ill.

,1 y 1 7 g 57 ABSTRACT [22] May 9 2 A gas diffuser including aconically-shaped diffuser [2i] Appl. No.1 257,123 cone having aplurality of openings formed along the base circumference of the conefor liberating small gas bubbles. Connected to an opening formed in theapex 8i. of the cone is a hydrostatic leg depending therefrom The lengthof the hydrostatic leg is designed such that [58] Field of Search261/124 during normal operation no gas will pass therethrough. [56]References Cited The openings in the diifuser cone include anouterentrance opening and a recessed inner entrance opening. UNITEDSTATES PATENTS The inner opening is of square shape to release a small1,984,716 12/1934 Welhoefer 261/124 bubble, The top of the diffuser coneincludes 3' unique g i i 9 9 seat and latch connecting arrangement thatenables ap es ay 3,214,151 10/1965 Meunier 261/124 n??? 3353 22222 32: man openmg m gas header 3,255,887 6/1966 Walker et a]. 261 124 p p y g3,334,819 8/1967 Olavson 26111 24 10 Claims, 5 Drawing Figures 5 i M 432 E if {X GAS nilrriisnn BACKGROUND OF THE INVENTION This inventionrelates to a gas diffuser and more particularly to a gas diffuser of thetype used for the aeration of liquids in a large tank such as those usedfor sewage treatment.

Placing a gas in solution by diffusion is accomplished by three majormechanisms. The first portion of the absorption phase occurs at theinterfaces of the bubbles during formation. The second significantabsorption phase occurs as the bubbles rise to the liquid surface. Thebursting of the bubbles at the surface, along with the related surfaceturbulence produces the third important absorption phase. Theoptimization of these three transfer mechanisms is required to obtainmaximum gas absorption into the liquid.

The simplest approach to diffuse gas into a liquid involves passing thegas through an open end drop pipe. With this approach the bubbleinterface absorption phase, which is a function of bubble surface area,is in no way near optimum. Bubble rise and surface bursting are theprime absorption modes. This approach fails to take full advantage ofthe most significant interface phase and thus loses a great amount ofpotential absorption capability. Probably the most efficient solution tothe diffused aeration problem incorporates the use of a porous plate toform extremely small gas bubbles. This approach optimizes the interfaceabsorption but introduces serious clogging problems that render thediffuser useless unless cleaned frequently. This problem is particularlypresent when aerating domestic sewage or industrial wastes.

One of the more recent attempts to develop an improved diffuser isdisclosed in U. S. Pat. No. 3,501,133. The spargers disclosed thereininclude a cluster of upper orifices formed-therein for distributing gasto a cluster of rise points and a lower orifice spaced a distance belowthe upper orifices so as to liberate additional gas therethrough. Thegas released through the lower orifice is in the form of large bubbleswhich tend to coalesce with the smaller bubbles released from the upperorifices and thereby results in reduced oxygen transfer. These spargersare further connected to the gas supply header pipe in a manner whichincludes connecting ears which may be a place for potential ragbuild-up, which could well interfere with the transfer mechanisms of thedevice.

The gas diffuser of the present invention provides a device whichoptimizes the major transfer mechanisms and solves the problems alludedto above in a unique but simple manner.

SUMMARY OF THE INVENTION It is a primary object of the present inventionto provide a gas diffuser which optimizes the major transfer mechanismsrequired to obtain maximum gas absorption into the liquid.

Another object of the invention is to provide a gas diffuser having aunique means for fastening it to header pipes of different diameterswhich eliminates catching of rags and other stringy material often foundin sewage.

A further object is to provide a gas diffuser having gas diffusingopenings that releases small bubbles to obtain higher oxygen transferefficiency without substan tially increasing the tendency of theopenings to become clogged.

A still further object is to provide a gas diffuser that is simple indesign and inexpensive to manufacture.

These and other objects of the invention are realized by the presentinvention by providing a gas diffuser including a conically-shapeddiffuser cone having a plurality of openings formed along the basecircumference of the cone for liberating small gas bubbles. Connected toan opening formed in the apex of the cone is a hydrostatic leg dependingtherefrom for gravity removal of any solids that may accumulate withinthe system during no flow conditions. The length of the hydrostatic legis designed such that during normal operation no gas will passtherethrough. The openings in the diffuser cone include an outerentrance opening and a recessed inner entrance opening. The outeropening eliminates the larger particles that might clog up the smallerinner opening. The inner opening is of square shape because a squarehole will release a smaller bubble than an equivalent circular openingbecause of the tendency of the bubble to tear loose from the corners ofthe square openings.

The top of the diffuser cone incorporates a unique seat and latchconnecting arrangement that enables the diffuser to be installed in anopening in the gas header pipe in a manner which prevents the build-upof rags and other stringy materials. The latches on each side of theconnecting arrangement deflect as they are pushed into the header pipeopening and snap out past the opening, thus captivating the diffuserassembly. The seat is sealed by a gasket placed between the seat and theheader pipe. With the aid of the proper thickness of gasket, thediffuser can be installed on headers of various diameters.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features of theinvention will become apparent to those skilled in the art as thedisclosure is made in the following description of a preferredembodiment of the invention, as illustrated in the accompanying sheet ofdrawings, in which:

FIG. 1 is a vertical section of the gas diffuser of the presentinvention shown applied to the bottom of a gas header pipe;

FIG. 2 is a top plan view of the center portion of the diffuser capshowing the fastening means integral therewith;

FIG. 3 is a bottom plan view of the center portion of the diffuser capin FIG. 2;

FIG. 4 is a sectional view taken along line 4-% in FIG. 1 showing thediffuser fastening means; and

FIG. 5 is a top plan view of the diffuser cone showing the openingsformed therein.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, andmore particularly to FIG. ll, there is illustrated the: gas diffuser ofthe present invention secured to a gas header pipe 20. Gas diffuser m ispreferably formed from three basic parts: a diffuser cone 12, a diffusercap 141- having connecting means 16 integral therewith, and ahydrostatic leg 18 depending from diffuser cone 112.. These basic partsare preferably integrally molded from plastic materials such as ABSplastic or PVC plastic to reduce the weight of diffuser l0 and increaseits resistance to chemical corrosion.

Diffuser cone 12, the main body of diffuser 10, is an integrally formedinverted hollow conically-shaped member having an upper base portion 22and a lower apex portion 24, as best seen in FIGS. 1 and 5. Formed aboutthe outer periphery of base portion 22 are a plurality of rectangularshaped gas diffusing outlet openings 26. Openings 26 extend through the45 inclined side surface of cone 12 with their longer sides positionedin the vertical direction. The preferred embodiment includes eightequally spaced openings 26 spaced 45 apart around the upper edge of conel2. Openings 26 are approximately /2 inch in length and /8 inch inwidth. Apex portion 24 includes an opening 28 formed therethrough with adownwardly extending annular flange 29 formed thereabout for receipt ofhydrostatic leg 18.

Hydrostatic leg 18 extends downward from apex por tion 24 and is securedto flange 29 in communication with opening 28 preferably by a suitablesolvent bond, as seen in FIG. 1. Leg 18 is a hollow open ended pipe ofapproximately 7 /2 inches in length to prevent the discharge of gasthrough the bottom end thereof during normal operation of diffuser l0.Hydrostatic leg 18 is effective to provide an access for gravity removalof solids that may accumulate in header pipe 20 and cone 12 during noflow conditions.

Referring to FIG. 1, a circular diffuser cap 14 closes off the open baseportion 22 of cone l2. Cap 14 has a diameter substantially equal to thediameter of the outer edge of base portion 22 and is solvent bondedthereto in a suitable manner. Formed integral with the central portionof cap 14 is a connecting means 16 for seating and latching diffuser toheader pipe 20. Connecting means 16 includes an annular seating flange30 having a concave seating surface 32 extending upward from cap 14 ashort distance above the top surface thereof. Integral with the centralopening of flange 30 is a tubular latching member 34 which extendsupward above seating surface 32. Latching member 34 includes a pair ofopposing deflectable latching lugs 35 formed from the sides of member 34for locking diffuser 10 in a fixed relationship to header pipe 20. Lugs35 include outwardly extending flanges 36 having substantiallyhorizontal lower surfaces 37 and beveled upper surfaces 38, as best seenin FIG. 4. I

Positioned inwardly from the outer peripheral edge of cap 14 andintegral with the bottom surface thereof is an annular flange 40. Flange40 includes an outer surface 42 inclined 45 and positioned to contactthe inner surface of cone 12 at the base portion 22. Surface 42 extendsdownward approximately As inch so as to close off the upper half of gasdiffusing outlet openings 26 and effectively form openings ofa squareshape having 4 inch sides. Radially extending across the upper and lowersurface of cap 14 are a plurality of ribs 45 for reinforcing thestructural integrity of diffuser cap 14.

Gas diffuser 10 is installed in gas header pipe by positioning a sealinggasket 50 around latching member 34 and above seating surface 32, andthen pushing latching member 34 and latching lugs 35 interal therewiththrough an opening 55 in header pipe 20 of substantially the samediameter as member 34. Surfaces 38 of lugs 35 contact the periphery ofpipe opening 55 causing lugs 35 to deflect inward and permitting them topass through opening 55 at which point lugs 35 snap out past the inneredge of opening 55 captivating the diffuser 10 with surfaces 37 of lugs35 in contact with the inner surface of pipe 20. Sealing gasket iscompressed between seating surface 32 and header pipe 20.

By changing the thickness of gasket 50 the gas diffuser of the presentinvention may be attached to header pipes of different diameters.

In the operation of diffuser 10 of the present invention, gas underpressure from header pipe 20 passes successively through opening 55,member 34 into cone l2 and exits in the form of small bubbles throughoutlet openings 26. The distance between openings 26 and the bottomopening in hydrostatic leg 18 is approximately 10 inches which undernormal operating flow rates (i.e., 5 to 15 s.c.s.m.) are sufficient tobalance the gas pressure in cone l2 and the liquid pressure within leg18 to prevent the exiting of gas through the bottom end of leg 18. Byincreasing or decreasing the length of leg 18 the diffuser 10 may beadapted to handle flow rates respectively higher or lower than indicatedabove without exiting gas through leg 18. If the gas supply in headerpipe 20 is cut off, the header will fill with liquid and any solidparticles contained therein. When the gas supply is re-established, thegas will push the liquid and solid particles ahead of it along pipe 20through opening into cone 12 and out through the bottom end ofhydrostatic leg 18. The gas will push down through leg 18 to a level atwhich the gas pressure is balanced by the liquid pressure within leg 18,at which point the diffuser 10 will attain its normal operating flowrate and discharge gas bubbles only through openings 26 in cone l2.

Diffuser 10 is specifically designed to optimize the gas absorptionphase which occurs at the interfaces of the bubbles during formation atthe openings 26 and during bubble rise to the liquid surface. The areaof openings 26 has been optimized to create the smallest bubble possibleand still prevent clogging thus introducing into the liquid the maximumratio of surface area of the bubble to the volume of the bubble. It issignificant that the openings 26 are square (approximately A; inch oneach side) in lieu of the traditional round openings. A square openingwill release a smaller bubble than an equivalent circular openingbecause of the tendency of the bubble to tear loose from the corners ofa square opening. As soon as the bubble breaks from one corner, it willbe released. This early release is caused by the unusual forces causedby forming a round bubble from a square opening. With a circularopening, the early release is not realized since the shape of the bubbleis round and conforms to the opening without any unusual forces. Toobtain release of bubbles of equal size, the circular opening must besmaller. With a smaller size opening comes the increased danger ofclogging.

The conical shape of diffuser cone 12 is effective to increase thevelocity of the liquid as it rises past the diffuser. As the area of thewater column is decreased by increasing the area occupied by diffusercone 12, the velocity of the water in the near proximity of cone 12 willalso increase. The maximum velocity will thus be reached at the top ofbase 26 of cone 12. This increased velocity increases the transferefficiency of diffuser 10 in two ways. First, the increased velocitycauses a turbulence area immediately above cone 12. The conical shape ofdiffuser cone 12 in conjunction with the flat cap 14 also increases theturbulence above cone 12 because of the hydraulic patterns produced fromthis unique combination. This turbulence area breaks the already smallbubbles into even smaller bubbles by the hydraulic shear created by theturbulence. Of course, smaller bubbles obtain higher efficiency becauseof the higher surface area to volume ratio of the smaller bubblescompared to the bubbles before the area of high turbulence. Secondly,the increased force of the liquid passing by diffuser outlet openings 26breaks the bubbles loose from the openings when they are smaller with asimilar increase in transfer efficiency. Further, by releasing thebubbles at the top edge of cone 12 in an area of high turbulence andhigh velocity the amount of bubble coalesence is minimized.

The specific manner in which the square openings are formed byrectangular openings 26 in cone 12 in combination with annular flange 40on diffuser cap lld helps decrease the clogging of the openings. Theouter rectangular opening eliminates the larger particles which mightclog up the smaller inner opening. Elimination of the larger particlesis also accomplished by the fact that the inner opening from which thebubble emits is recessed away from the outer surface. The conical shapeof diffuser cone l2 and the specific design of connecting means 16 donot provide obstructions which could possibly catch rags and otherstringy material often found in sewage which could interfere with thetransfer mechanism of the diffuser.

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and the scope of the invention as set forth inthe appended claims.

What is claimed is:

l. A gas diffuser for liberation of gas below the surface of a liquidcomprising a hollow conically-shaped body member having an upper baseportion and a lower apex portion, said base portion having a cap closingoff said base portion and said apex portion having an opening formedtherethrough, a hydrostatic leg extending downward from said apexopening having an upper open end in communication with said apex openingand a lower open end spaced therebelow, said base portion having aplurality of gas diffusing outlet openings formed therein about theouter periphery thereof, said cap having an inlet opening centrallyformed therein to receive a supply of gas from a gas supply header andsaid lower open end of said hydrostatic leg being spaced a sufficientdistance below said gas diffusing outlet openings to prevent gas fromexiting there through.

2. A gas diffuser of the type secured to a gas header pipe for theliberation of gas near the bottom of a sewage treatment tank,comprising: a hollow conicallyshaped body member having an upper baseportion and a lower apex portion, said base portion having a cap closingoff the upper end thereof, said cap having an inlet opening centrallyformed therein in fluid communication with the underside of said headerpipe, said apex portion having an opening formed therethrough; ahydrostatic leg extending downward from said apex opening having anupper open end in communication with said apex opening and a lower openend spaced therebelow; and a plurality of gas diffusing outlet openingsformed about the outer periphery of said base portion said lower openend of said hydrostatic leg being spaced a sufficient distance belowsaid gas diffusing outlet openings to prevent gas from exitingtherethrough during normal operation of the gas diffuser.

3. The invention as defined in claim 2 wherein said gas diffusing outletopenings are of a substantially square shape.

4. The invention as defined in claim 2 wherein said gas diffusing outletopenings are of a substantially rectangular shape and said cap includesa downwardly pro jecting annular flange which is positioned to block offthe upper portions of said gas diffusing outlet openings at the innersurface thereof so as to define gas diffusing outlet openings that areeffectively of a substantially square shape.

5. The invention as defined in Claim 2 wherein said cap includesconnecting means associated therewith for connecting said gas diffuserto said header pipe.

6. The invention as defined in claim 5 wherein said connecting meansincludes a tubular latching member having a first open end secured tosaid cap in fluid communication with the interior thereof and a secondopen end in fluid communication with the interior of said header pipe,said second open end having latch means associated therewith forsecurely connecting said top portion to said header pipe.

'7. The invention as defined in claim 6 wherein said cap includesannular seat means positioned about said latching member and sealingmeans being provided between said seat means and said header pipe.

8. The invention as defined in claim 7 wherein said latch means includesa plurality of semi-rigid connecting lugs formed from said tubularconnecting members, said lugs having outwardly extending flanges formedintegral with the upper ends thereof for contacting the inner surface ofsaid header pipe and thereby securing said gas diffuser in place.

9. A gas diffuser of the type secured to a gas header pipe for theliberation of gas near the bottom of a sewage treatment tank,comprising: a hollow conicallyshaped body member having an upper baseportion and a lower apex portion, said base portion having a cap closingoff the upper end thereofQsaid cap having an inlet opening centrallyformed therein in fluid communication with the underside of said headerpipe, said apex portion having an opening formed therethrough; ahydrostatic leg extending downward from said apex opening having anupper open end in communication with said apex opening and a lower openend spaced therebelow; a plurality of rectangular gas diffusing outletopenings formed about the outer periphery of said base portion, said caphaving an annular flange associated with the underside thereofpositioned to close off a portion of said outlet openings so as toeffectively form outlet openings of a substantially square shape, saidlower open end of said hydrostatic leg being spaced a sufficientdistance below said gas diffusing outlet openings to prevent gas fromexiting therethrough during normal operation of the gas diffuser;connecting means associated with said cap for connecting said gasdiffuser to said header pipe, said connecting means including a tubularlatching member having a first open end secured to said cap in fluidcommunication with the interior thereof and a second open end in fluidcommunication with, the interior of said header pipe, said second openend having latch means associated therewith for securely connecting saidtop portion to said header pipe; and annular seating means positionedabout said latching member for compressing integral with the upper endsthereof for contacting the inner surface of said header pipe and therebysecuring said gas diffuser in place with said sealing gasket compressedbetween said seating means and said header pipe.

*zgz gy UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.790,142 Dated February 5 1974 In t Brian L. Goodman, Robert B. Higginsand Frank M. Denham It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

In column 3, line 12, delete "1/2" and insert --l/4--.

In column 3, line 21, delete "7-1/2" and insert In column 3, line 60,delete "interal" and insert --integral--.

iL-igne-d and scaled this 7th day of May 19%..

C JDRRSFJXLL DAI-EN Commissioner of Patents

1. A gas diffuser for liberation of gas below the surface of a liquidcomprising a hollow conically-shaped body member having an upper baseportion and a lower apex portion, said base portion having a cap closingoff said base portion and said apex portion having an opening formedtherethrough, a hydrostatic leg extending downward from said apexopening having an upper open end in communication with said apex openingand a lower open end spaced therebelow, said base portion having aplurality of gas diffusing outlet openings formed therein about theouter periphery thereof, said cap having an inlet opening centrallyformed therein to receive a supply of gas from a gas supply header andsaid lower open end of said hydrostatic leg being spaced a sufficientdistance below said gas diffusing outlet openings to prevent gas fromexiting therethrough.
 2. A gas diffuser of the type secured to a gasheader pipe for the liberation of gas near the bottom of a sewagetreatment tank, comprising: a hollow conically-shaped body member havingan upper base portion and a lower apex portion, said base portion havinga cap closing off the upper end thereof, said cap having an inletopening centrally formed therein in fluid communication with theunderside of said header pipe, said apex portion having an openingformed therethrough; a hydrostatic leg extending downward from said apexopening having an upper open end in communication with said apex openingand a lower open end spaced therebelow; and a plurality of gas diffusingoutlet openings formed about the outer periphery of said base portionsaid lower open end of said hydrostatic leg being spaced a sufficientdistance below said gas diffusing outlet openings to prevent gas fromexiting therethrough during normal operation of the gas diffuser.
 3. Theinvention as defined in claim 2 wherein said gas diffusing outletopenings are of a substantially square shape.
 4. The invention asdefined in claim 2 wherein said gas diffusing outlet openings are of asubstantially rectangular shape and said cap includes a downwardlyprojecting annular flange which is positioned to block off the upperportions of said gas diffusing outlet openings at the inner surfacethereof so as to define gas diffusing outlet openings that areeffectively of a substantially square shape.
 5. The invention as definedin claim 2 wherein said cap includes connecting means associatedtherewith for connecting said gas diffuser to said header pipe.
 6. Theinvention as defined in claim 5 wherein said connecting means includes atubular latching member having a first open end secured to said cap influid communication with the interior thereof and a second open end influid communication with the interior of said header pipe, said secondopen end having latch means associated therewith for securely connectingsaid top portion to said header pipe.
 7. The invention as defined inclaim 6 wherein said cap includes annular seat means positioned aboutsaid latching member and sealing means being provided between said seatmeans and said header pipe.
 8. The invention as defined in claim 7wherein said latch means includes a plurality of semi-rigid connectinglugs formed from said tubular connecting members, said lugs havingoutwardly extending fLanges formed integral with the upper ends thereoffor contacting the inner surface of said header pipe and therebysecuring said gas diffuser in place.
 9. A gas diffuser of the typesecured to a gas header pipe for the liberation of gas near the bottomof a sewage treatment tank, comprising: a hollow conically-shaped bodymember having an upper base portion and a lower apex portion, said baseportion having a cap closing off the upper end thereof, said cap havingan inlet opening centrally formed therein in fluid communication withthe underside of said header pipe, said apex portion having an openingformed therethrough; a hydrostatic leg extending downward from said apexopening having an upper open end in communication with said apex openingand a lower open end spaced therebelow; a plurality of rectangular gasdiffusing outlet openings formed about the outer periphery of said baseportion, said cap having an annular flange associated with the undersidethereof positioned to close off a portion of said outlet openings so asto effectively form outlet openings of a substantially square shape,said lower open end of said hydrostatic leg being spaced a sufficientdistance below said gas diffusing outlet openings to prevent gas fromexiting therethrough during normal operation of the gas diffuser;connecting means associated with said cap for connecting said gasdiffuser to said header pipe, said connecting means including a tubularlatching member having a first open end secured to said cap in fluidcommunication with the interior thereof and a second open end in fluidcommunication with the interior of said header pipe, said second openend having latch means associated therewith for securely connecting saidtop portion to said header pipe; and annular seating means positionedabout said latching member for compressing sealing gasket between saidseating means and said header pipe.
 10. The invention as defined inclaim 9 wherein said latch means includes a plurality of semi-rigidconnecting lugs formed from said tubular connecting member, said lugshaving outwardly extending flanges formed integral with the upper endsthereof for contacting the inner surface of said header pipe and therebysecuring said gas diffuser in place with said sealing gasket compressedbetween said seating means and said header pipe.